Xicor Corporation

Jeffrey Sung

John M Caywood

William H Owen

Ping Wang

Joseph Drori

James M Jaffe

Isao Nojima

A field-programmable redundancy apparatus for integrated circuit semiconductor memory arrays is disclosed. The present invention allows the user to replace a defective memory cell with a redundant memory cell while the integrated circuit memory array is in the field. The user communicates with the redundancy apparatus over standard signal paths of the integrated circuit semiconductor memory array and with standard voltage levels. The redundancy apparatus detects a predetermined code sequence on one or more of the address and data lines of the memory array to enter a special redundancy-reconfiguration mode. In the reconfiguration mode, the redundancy apparatus provides information on the availability and functionality of the redundant memory cells and enables the user to replace a defective memory cell with a selected redundant memory cell. The field-programmable redundancy apparatus may comprise nonvolatile memory means, such as EEPROM's, to store the replacements of primary memory cells with redundant memory cells. In the reconfiguration mode, detection of a second predetermined code sequence causes the reconfiguration mode to be exited.

Field-programmable redundancy apparatus for memory arrays

A field-programmable redundancy apparatus for integrated circuit semiconductor memory arrays is disclosed. The present invention allows the user to replace a defective memory cell with a redundant memory cell while the integrated circuit memory array is in the field. The user communicates with the redundancy apparatus over the standard signal paths with standard voltage levels of the integrated circuit semiconductor memory array. The redundancy apparatus detects a predetermined code sequence on one or more of the address and data lines of the memory array to enter a special redundancy-reconfiguration mode. In the reconfiguration mode, the redundancy apparatus provides information on the availability and functionality of the redundant memory cells and enables the user to replace a defective memory cell with a selected redundant memory cell. The field-programmable redundance apparatus may comprise nonvolatile memory means, such as EEPROM's, to store the replacements of primary memory cells with redundant memory cells. In the reconfiguration mode, detection of a second predetermined code sequence causes the reconfiguration mode to be exited.

Growing community of inventors

Saratoga, CA, United States of America

Jeffrey Sung